Sample preparation is one of the key functions in detection of biologically important organisms. It involves controlled separation, concentration, and/or manipulation of desired particles from a matrix of interferents. Traditionally, it is performed through separate, standalone centrifugation, magnetic manipulation and filtration systems and then transferred to a detector. The main disadvantages are cross-contamination, slow operational speed, high cost and the need for skilled personnel. Recent efforts are towards the development of lab-on-a-chip systems (“LOC”) with on-chip sample preparation and detection capabilities. Although LOC offers advantages of reduced reagent consumption and reduced waste generation, multiplexing, portability and scalability, the integration of on-chip sample preparation is yet to be realized. This is because of the necessity of processing large sample volumes that is difficult in existing chip platforms. Technologies that can seamlessly integrate sample processors to LOC and that can handle large sample volumes for a fully automated; rapid real-time monitoring is critically needed for health and environmental monitoring applications.
What is needed is a method and associated system for accumulating and concentrating a selected species that provides reasonably high throughput and good selectivity and should not require a large “footprint” in order to operate. Preferably, the approach should extend to a large class of species, should not require that the selected species be electrically charged or labeled with functional moieties, and should allow use of smaller voltages for operation.